The present invention relates generally to cabin pressure control systems. More specifically, the present invention relates to an outflow valve for a cabin pressure control system.
Commercial aircraft are equipped with cabin pressure control systems for controlling pressure differences between ambient and cabin pressures. During the flight of an aircraft, variations in aircraft altitude cause rapid changes in ambient pressure. The cabin pressure control system maintains the cabin pressure at a relatively comfortable level and makes gradual changes in the cabin pressure to minimize passenger discomfort.
A typical cabin pressure control system for a commercial aircraft includes an outflow valve located at the aft end of the aircraft. For large aircraft such as the Boeing 777, a second outflow valve is located at the forward end. Pressure inside the aircraft cabin can be controlled by regulating the flow of cabin air out of the outflow valve(s).
During operation of the cabin pressure control system, cabin air rushes through the outflow valve(s) and, at certain times, makes noise. Passengers inside the cabin can hear the noise as a single tone. The noise is not deafening; however it can be very irritating to passengers and crew members, especially over a long flight.
Airline carriers have identified a need to suppress the noise generated by the outflow valves, especially for the large commercial aircraft having more than one outflow valve.